Question

if you react 120g of c2h6 with 320g of o2 what is the limiting reagent?

Answer 1

Molar mass of $O_2=32g$

Moles of $O_2=\frac{320}{32}=10$

Molar mass of $C_2H_6=30g$

Moles of $C_2H_6=\frac{120}{30}=4$

$2C_2H_6+7O_2\to 4CO_2+6H_2O$

$4$ moles of $C_2H_6$ requires

$\frac {4}{2}×7=14$ moles of $O_2$

The available moles of $O_2$ are 10

$10$ moles of $O_2$ requires

$\frac{10}{7}×2= 2.8$ moles of $C_2H_6$

Therefore, $O_2$ is the limiting reagent.